In a mobile phone or other portable electronic device, a substrate is sandwiched between a front case and a rear case, and the cases are fastened to each other by screws inserted in the stacking direction (see for example, Patent Document 1). Further, in such housing structures, ones having frames for placement of the substrate and a display unit are known as well (Patent Document 2).                Patent Document 1: Japanese Patent Publication (A) No. 2000-209314        Patent Document 2: Japanese Patent Publication (B) No. 7-202469        